Spherical coil for variometers



Aug. 12, 1947;

E. E. COMBS SPHERICAL COIL FOR VARIOMETERS OriginaIFiled Sept. 6, 1944INVENTOR.

EDWARD E. COMBS Patented Aug. 12, 1947 SPHERICAL COIL FOR VARIOMETERSEdward E. Combs, Long Branch, N. J.

Original application September 6, 1944, Serial No. 552,859. Divided andthis application October 4, 1945, Serial No. 620,375

(Granted under the act of March 3, 1883, as

4 Claims.

amended April 30, 1928; 370 0. G. 757) The invention described hereinmay be manufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereon.

This invention relates to spherical coils used in radio tuning circuits.The invention discloses the structural features of the spherical coils,the method of winding such coils having been disclosed in a parentapplication 552,859, filed September 6, 1944, titled Spherical coils forvariometer, this application being a division of the parent application.

It is very well known in the radio art that the spherical coils whenused in connection with variometers are much more effective than thecylindrical coils because the spherical coil rotor may be coupled muchcloser to the cylindrical stator of the variometer thus enabling one tospan much wider frequency band with the variometers of this type, thecombination being capable of replacing as many as six fixed R. F. coils.Although the advantages of the spherical coils are well known in theart, their use has been somewhat limited because no simple manufacturingmethods were available, and, as a consequence, the majority ofvariometers used cylindrical rotors.

The invention discloses structural features of the spherical radio coilswhich support the wire, the latter having been given a spherical formduring the winding operation of the coil. The winding methods and jigsfor the coils of this type are disclosed in the parent application, andthis application discloses the structural features of the coils producedaccording to the previously disclosed winding methods.

It is therefore an object of this invention to provide spherical radiocoils having improved structural and electrical features.

These and other features of the invention will be more clearlyunderstood from the following detailed description and the accompanyingdrawing in which the only figure discloses a perspective view of thecoil form.

It is known in the radio art that uses of the variometer are encounteredwhich subject the coils to such heavy loads that the current-carryingwire reaches sufiiciently high temperature either to melt or carbonizethe Wire supporting elements made of plastics. The use of plastics formaking the wire supporting elements is always desirable because of theirresistances to shock. However, when the radio coils are heated to suchhigh temperatures, the use of the plastics for supporting the wire isimpossible and materials which can Withstand high temperatures, such asceramic materials, must be used in their stead. In the prior art it hasbeen known to use ceramic bridges for supporting the wire; however, thecoils with the ceramic bridges invariably used ceramic disks or ceramicrings for supporting them which rendered the entire coil frame verybrittle and not capable of resisting severe mechanical shocks. Theinvention discloses a coil frame in which the bridges are made ofceramic material while the ring supporting the bridges is made ofplastics, the resilient properties of the plastics making the coil framemore suitable for resisting very severe mechanical shocks.

Referring to the drawing, the wire supporting bridges H! are made ofceramic material, the bridges being mounted on a ring l2 made ofplastic. The outer surfaces I3 of the bridges are grooved for holdingthe wire and the inner ends of the same bridges are provided withextensions l4 and [6 which fit into recesses l5 provided for thispurpose in ring 12. In order to stiffen the structure still further theceramic bridges and the ring may be provided with suitable holes l8which are used for mounting pins I9 made of plastic which act asadditional elastic means for holding the ceramic bridges in an elasticengagement with the ring. A two-piece shaft 20 and 22 of the coil ismounted on ring l2 by means of threaded ends 24 and nuts 26 (only oneend is visible in the figure). The wound wire is connected to the shaftby means of lugs 28.

The advantage of the structure illustrated in the figure resides in thefact ring I2 is made of plastic thus providing a resilient support forthe ceramic pieces, the resiliency of the ring and the resiliency of theconnections between the ring and the bridges contributing markedly tothe ability of the coil to absorb severe mechanical shocks. In the priorart ring 12 is made of ceramic materials which produce a very brittleframe not capable of absorbing severe mechanical shocks. The mechanicalshocks are transferred to the surfaces interconnecting the bridges withthe ring which produces cracking of the joints. This is not the case inthe disclosed structure because the ring acts as a shock-absorbingmedium. When the shocks are transmitted through the shaft pieces 20 and22.to the ring the shock is absorbed to a very large extent by the ringand is transferred to the bridges in a sufiiciently subdued form so asto prevent cracking of the ceramic pieces at the joints. When the ringis made of the ceramic material it ordinarily cracks resulting in thecollapse of the entire coil.

The methods for winding the spherical coil frames of the type disclosedin this specification are disclosed in the previously mentioned parentapplication and in the co-pending application of N. T. Volsk, S. N.561,800, filed November 3, 1944, titled Jig for winding spherical coils,now Patent No. 2,394,023.

While the invention has been described with reference to a particularembodiment, it will be understood that various modifications of theapparatus shown may be made within the scope of the following claims.

I claim:

1. A frame for a. spherical radio coil including a ring made of plasticmaterial, a plurality of ceramic bridges symmetrically and radiallydisposed around, and fastened to, said ring, the outer ridge surfaces ofeach bridge forming spaced wire supports for said coil, and a twopiececoil shaft fastened to said ring.

2. A frame for a spherical radio coil as defined in claim 1 whichfurther includes extensions at the inner ends of said bridges, andrecesses on both sides of said ring, said extensions fitting into saidrecesses.

3. A frame for a spherical radio coil including a ring made of plastic,a plurality of pairs of aligned rectangular recesses along the two edgesof said ring, a plurality of ceramic bridges radially disposed aroundand resting on said ring, two rectangular extension at the inner end ofeach of said bridges, said extensions fitting into the correspondingrecesses on said ring, and a two-piece metallic shaft connected to saidring for rotatively supporting said coil and for electrically connectingsaid coil to outside circuits.

4. A frame as defined in claim 3 which further includes pins made ofplastic interconnecting said bridges and said ring.

EDWARD E. COMES.

